$1.$ Demand management involves modifying or influencing demand in several ways. Which of the following items was not listed as a way of modifying or influencing demand?

a$.$ Pricing $$ differential pricing used to increase peak demand or to build up demand in off$-$peak periods

b$.$ Advertising and Promotion $$ used to stimulate and$/$or smooth out demand

c$.$ Backlogs and Reservations $$ customers waiting for late orders $($backlog$)$ or reserving capacity in advance

d$.$ Development of complementary offerings $$ firms with seasonal products$/$services may seek products$/$services in demand at other times of the year